1. Field of the Invention
The present invention relates to a rear projection television, more particularly to anoptical assembly for rear projection television.
2. Description of the Related Art
In recent years, as the opto-electronic technology grows rapidly, the visualization of information becomes more and more important. The significance and demand for rear projection television as a display device increases drastically. Therefore, with the consideration of mass production and labor cost, the way of conveniently and quickly assembling a rear projection television, saving manpower and cost, and maintaining a high-brightness and high-resolution video quality to provide comfortable viewing screens for users, and being capable of quickly and conveniently processing the after-sale service and maintenance to strengthen the competitiveness in the market and popularly accepted by the consumer""s market has become an important subject of the research and development in the industry.
Please refer to FIG. 1 for the overall optical system structure of a prior-art rear projection television. A screen 10 in the front, a base 11 at the bottom, and a rear cover 12 at the backside constitute the interior of the rear projection television; wherein the interior of the rear projection television has a carrier 13 on the base 11, and the carrier 13 has an optical engine 14 on it. A first mirror 15 is fixed in the front of the optical engine 14, and furthermore a second mirror 16 is disposed on the inner side of the rear cover 12 at the back of the screen 10. The operation of the optical system of the rear projection television is by means of generating a beam with video information from the optical engine 14 on the carrier 13 and projecting the beam onto the first mirror 15. The beam is then reflected onto the second mirror 16 from the first mirror 15, and finally onto the screen 10, which constitutes the optical system projection architecture.
Since every component of the optical system of the rear projection television must have an accurate relative position and a projection angle to assure the distortion-free and aberration-free image produced by the optical system of the rear projection television, and such system has to be assembled in a clean room to prevent the optical components from being contaminated and to maintain a high-brightness and high-resolution video quality. However, the components of the optical system of the rear projection television such as the optical engine 14, the first mirror 15, the second mirror 16, and the screen 10 are fixed individually on different major component units; there is not only error in the manufacture of the components, but also error in the manufacturing of the assembly. These errors will seriously affect the video quality of the screen. In the meantime, the illumination source and electronic components that easily generate heat are accommodated in the interior of the rear projection television with the optical components. Such arrangement is not only difficult to disperse heat, but the expansion and contraction due to temperature also affects the imaging quality of optical components. In addition, the whole set of the prior-art rear projection television has to be assembled in the clean room to prevent contamination by dust, and in turn will cause a higher manufacturing cost. It needs to disassemble the whole television set for the maintenance of optical components, which also makes the maintenance more difficult. Therefore, there are many shortcomings of the prior-art rear projection television, which require improvement.
The objective of the present invention is to provide an optical assembly for rear projection television, such that when the rear projection television is assembled, it minimizes the assembling error, and thus maintains good video quality.
The other objective of the present invention is to provide an optical assembly for rear projection television, which only requires unscrewing a small number of screws to remove the optical assembly, so that the optical system can be disassembled without affecting the relative position of the components of the optical system, which facilitates the maintenance very much.
A further objective of the present invention is to provide anoptical assembly for rear projection television wherein the projectingoptical components and heat generating components are separated, so that the video will not be affected by heat and thus maintains good video quality of the screen.
Another further objective of the present invention is to provide anoptical assembly for rear projection television, wherein the optical system has a sealed space so that when the rear projection television is assembled, only the optical system has to be assembled in a clean room, which can reduce the cost and make the maintenance simpler and more convenient.
To accomplish the aforementioned objectives, the rear projection television of the present invention comprises an optical assembly; an optical engine disposed on the lower carrier the optical assembly; a hood member coupled to an end of the carrier at the front end of the optical engine; an inlet disposed on the hood member, the inlet having an elastic sealed cover which allows the projection lens of the optical engine to be extended inside the hood member and closely wraps the external diameter of the projection lens; a first mirror disposed in front of the projection lens; a second mirror is disposed on the upper end of the inner side of the hood member along the optical path of the small reflective projection lens. A screen is coupled to the outlet of the hood member along the optical reflection path of the second mirror. Covering the components one by one by means of a hood member and a screen according to the size of the optical path and excluding the optical engine of the heat-generating element outside constitute a sealed space with an isolation of air from the exterior for preventing the external dust, moisture, and temperature. Thus, such arrangement constitutes an optical assembly of the present invention.